Xoutpost.com - 2003 E320- HELP

My mom's 2003 E320 is not starting everytime I crank it. The cranking sequence will start, everything is fine until the cranking motor is cranking and the engine will not start. I need to turn the car off, re-crank the car and hope for the best for the car to start up. It starts up everyday, but it usually takes 2-3 tries to actually crank the vehicle.

My 2004 x5 is still running fine and fires right up~ only thing is that it has 82k miles and my e320 has only 45000 miels. Which kinda tells me to not walk into the mercedes dealer again.

I know this is X5 forum, but if any of you have idea, please throw it out, I maintain my X5 myself upto this point so I can try a few technical things if you throw it out. Thanks for your help!